Carbon atoms are the basis for all life on earth. Carbon atoms are found in all the molecules that make up living organisms-carbohydrates, lipids, proteins, and nucleic acids. Why is carbon important in the earth's ecosystems? A. Carbon originates in sunlight. B. Carbon is produced in the nitrogen cycle. C. Carbon atoms are found in molecules of all living organisms. D. Carbon atoms are found only in nonliving matter.

The correct answer is C. Carbon atoms are found in molecules of all living organisms.

Carbon is compound of the organic complex molecules and has unusual ability to form polymers. Because of its tetravalent properties (able to form four covalent chemical bonds), carbon is often bonded with many other elements, especially oxygen, hydrogen and nitrogen which enables this element to serve as a common element of all known life.